=SUM(IF(IF(MATCH(Table1[Ivoice],Table1[Ivoice],0)=ROW(Table1[Ivoice])-ROW(Table1[[#Headers],[Ivoice]]),(ROW(Table1[Ivoice])-ROW(Table1[[#Headers],[Ivoice]])),0)<>0,Table1[Totals],""))
Can someone break this down, and explain this formula to me. I know what it does, but not clear of the meaning...